Kinetic AC/DC Converter for Electromagnetic Energy Harvesting in Autonomous Wearable Devices

A nano-power integrated circuit is designed to convert the ac output of an electromagnetic micro generator for wearable kinetic energy harvesting to dc usable power. The converter is designed to minimize the quiescent current and to maximize the energy conversion and maximum power point tracking efficiency from the kinetic energy harvester. The architecture implements an ac/dc chopper exploiting the intrinsic inductance of the transducer combined with a zero-drop rectifier. An optimal switching scheme is derived for the converter and a corresponding control circuit is developed and optimized for low power consumption. The converter is designed in an SMIC 130-nm process, and circuit simulations show an efficiency of 87%-88% with respect to the maximum power point of the transducer with a battery supply voltage ranging from 3.5 V to 4.2 V. The quiescent current of the converter is as low as 250 nA.